How soon: Rinsing flux residue from baseboard radiators

Hi,
I'm in the process of putting in baseboard radiators and won't have them connected to the system for several weeks. They are 3/4" fin-tube M type copper. Is it OK to wait several weeks before flushing out the flux residue from soldering. I won't be able to flush the radiators until my primary and secondary loops are interconnected between my boiler and my supply/return manifolds. Right now, the primary and secondary loops are non-existent, as well as the manifold, pumps, etc..